Here's a Zeppelin great,nobody,as far as i know, has ever posted this, it's not a very popular Zeppelin  
but here it is. 
Play with a slide. 
 
-|----------------------------------------------------------------------------| 
-|----------------------------------------------------------------------------| 
-|-3\0-3\0-3\0--/12-12-12-12--3\0-3\0-3\0--/12-12-12-12-----------------------| 
-|-3\0-3\0-3\0--/12-12-12-12--3\0-3\0-3\0--/12-12-12-12-----------------------| 
-|----------------------------------------------------------------------------| 
-|----------------------------------------------------------------------------| 
  That's the main riff anyway.  Please e-mail me w/ any suggestions.